Description

Revision Numbers Are Different Now

In CVS, revision numbers are per-file. This is because CVS
stores its data in RCS files; each file has a corresponding RCS
file in the repository, and the repository is roughly laid out
according to the structure of your project tree.

In Subversion, the repository looks like a single
filesystem. Each commit results in an entirely new filesystem
tree; in essence, the repository is an array of trees. Each of
these trees is labeled with a single revision number. When
someone talks about “revision 54”, they're talking
about a particular tree (and indirectly, the way the filesystem
looked after the 54th commit).

Technically, it's not valid to talk about “revision 5
of foo.c”. Instead, one would say
“foo.c as it appears in revision
5”. Also, be careful when making assumptions about the
evolution of a file. In CVS, revisions 5 and 6 of
foo.c are always different. In Subversion,
it's most likely that foo.c did
not change between revisions 5 and
6.

Similarly, in CVS a tag or branch is an annotation on the
file, or on the version information for that individual file,
whereas in Subversion a tag or branch is a copy of an entire
tree (by convention, into the /branches
or /tags directories that appear at the top
level of the repository, beside /trunk). In
the repository as a whole, many versions of each file may be
visible: the latest version on each branch, every tagged
version, and of course the latest version on the trunk
itself. So, to refine the terms even further, one would often
say “foo.c as it appears in
/branches/REL1 in revision
5.”